The following have been known as techniques relating to the present invention:
(1) a liquid aspirator comprising a motor for inserting an aspirating pipette into a liquid container so as to press the tip of the aspirating pipette against the bottom of the container, and detecting means for detecting the pressed state, wherein the detecting means includes a liquid container support table urged by a spring and an optical detector or an electromotive detector of the motor, thereby securing the contact of the tip of the aspirating pipette with the bottom of the liquid container (disclosed in, for example, Int'l Pat. Appln. Publication No. 00/58,736); and
(2) a liquid aspirator configured such that when liquid contained in a container for containing the liquid therein is aspirated by the use of an elevatable aspiration nozzle by descending the aspiration nozzle down to the bottom of the container in an elastically abuttable manner, the aspiration nozzle is descended at a predetermined descending speed from its top dead center down to a descendant level which has been previously set such that the tip of the nozzle is brought into contact with the bottom of the container with a high possibility, and thereafter, the aspiration nozzle is descended at a speed lower than the predetermined descending speed (disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication No. 271,322/1999).
However, the above-described conventional devices have required a mechanical mechanism for bringing the aspirating pipette and the liquid container into an elastic contact with each other or an optical or electric detecting mechanism for detecting the contact condition, thereby raising a problem of a complicated configuration.